Key Concepts

Review core concepts you need to learn to master this subject


// Create an ArrayList that stores Strings: ArrayList<String> months = new ArrayList<String>(); // Add values to the end of the ArrayList: months.add("January"); months.add("March"); // Add values to a specified index in the ArrayList: months.add(1, "February"); // Access a value from the ArrayList: System.out.println(months.get(0)); // Prints: January // Remove a value from the ArrayList: months.remove("February"); months.remove(0); // Removes the zeroeth element

An ArrayList is a built-in data structure that uses a dynamic array to store its elements.

In order to use this data structure, you must import java.util.ArrayList at the top of your program.